#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#define rep(i, s, e) for (ll i = s; i < e; i++)
#define upmax(a, b) a = max(a, b)
#define upmin(a, b) a = min(a, b)
using namespace std;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using pll = pair<ll, ll>;
using vpll = vector<pll>;
using vvpll = vector<vpll>;
const ll INF = 1e18;
struct tr {
ll l, r;
ll lazy_val = -1;
tr* lp = nullptr, * rp = nullptr;
tr(ll l, ll r) : l(l), r(r) {
if (l == r - 1) {
lazy_val = -1;
return;
}
push();
lp = new tr(l, (l + r) / 2);
rp = new tr((l + r) / 2, r);
}
void push() {
if (lazy_val == -1) return;
upmax(lp->lazy_val, lazy_val);
upmax(rp->lazy_val, lazy_val);
lazy_val = -1;
}
// Update the range [f,t) to val
void update(ll f, ll t, ll val) {
if (f >= r || t <= l) return;
if (l >= f && r <= t) {
lazy_val = val;
return;
}
push();
lp->update(f, t, val);
rp->update(f, t, val);
}
ll query(ll idx) {
if (idx >= r || idx < l) return -1;
if (l == r - 1) {
return lazy_val;
}
push();
ll v1 = lp->query(idx);
ll v2 = rp->query(idx);
if (v1 == -1) return v2;
return v1;
}
};
void solve() {
ll n, q;
cin >> n >> q;
vvpll queries(n);
vll maxL(n, -1), minR(n, INF);
rep(i, 0, q) {
ll l, r, a;
cin >> l >> r >> a;
queries[a].push_back({ l, r });
upmax(maxL[a], l);
upmin(minR[a], r);
}
tr seg(0, n);
rep(i, 0, n) {
if (maxL[i] > minR[i]) {
rep(j, 0, n) cout << -1 << ' ';
cout << endl;
return;
}
//cout << maxL[i] << ' ' << minR[i] << endl;
if (minR[i] != INF && maxL[i] != -1) seg.update(maxL[i], minR[i] + 1, i);
}
vll ans(n);
set<ll> vals;
rep(i, 0, n) vals.insert(i);
rep(i, 0, n) {
ans[i] = seg.query(i);
if (ans[i] != -1) vals.erase(ans[i]);
}
vector<bool> vis(n, false);
rep(i, 0, n) {
//cout << "ans[i] = " << ans[i] << endl;
if (ans[i] == -1) {
//ans[i] = *vals.begin();
//vals.erase(vals.begin());
ans[i] = n + 1;
}
/*else if (vis[ans[i]]) {
auto it = vals.lower_bound(i);
if (it == vals.end()) {
rep(j, 0, n) cout << -1 << ' ';
cout << endl;
return;
}
ans[i] = *it;
vals.erase(it);
}*/
else if (ans[i] != -1) vis[ans[i]] = true;
}
rep(i, 0, n) cout << ans[i] << ' ';
cout << endl;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
solve();
}
